Inner lens optics for omnidirectional lamp

FIELD OF THE INVENTION

0001The subject matter of the present disclosure relates generally to lighting devices and, more particularly, to lighting devices using one or more LEDs as a light source and an optical element to provide an improved distribution of light.

BACKGROUND OF THE INVENTION

0002Conventional incandescent lamps such as the common A19 bulb size typically provide a relatively uniform distribution of light. Specifically, the intensity of light measured at a fixed distance but at different angles from a centerline axis through the bulb is relatively constant. In addition to consumer appeal, this uniformity may be necessary for certain applications.

0003As compared to incandescent lamps, other types of light emitting devices are available that have certain advantages. For example, light emitting diodes (LEDs) can provide a light output comparable to an incandescent lamp but at a significantly improved energy efficiency. Additionally, the lifetime of an LED lamp can be substantially longer than an incandescent lamp.

0004The LEDs can be configured in a lamp that includes a threaded base (sometimes referred to as an “Edison base”) such that it is interchangeable with conventional incandescent lamps. A diffuser can also be provided that, in addition to light scattering, can provide an LED lamp with a shape similar to that of conventional incandescent lamps. The color and intensity of light provided by the LED can also be similar to incandescent lamps.

0005However, certain challenges remain for the use of non-incandescent lamps. For example, LED lamps require an associated circuit board and generate significantly more heat than an incandescent lamp of comparable light output. In addition, LEDs act close to lambertian sources and thus they alone typically do not provide a uniformly distributed omnidirectional light output. LED devices are usually flat-mounted on a circuit board such that the light output is substantially along a line perpendicular to the plane of the circuit board.

0006As such, the circuit board and heat management features contribute to the optical losses different along each direction causing the non-uniformity of the light distribution from the LEDs. Providing more energy to the LEDs can increase the amount of light output, but still may not provide uniformity. However, this also increases the amount of heat generated, which will degrade LED performance unless additional thermal management is undertaken such as larger cooling features. Yet, the size of the overall lamp may be limited depending upon the intended application or conventional lamp form desired.

0007Accordingly, an optical element or lens for more uniformly distributing the light from a source that includes one or more LEDs or alternatively chip-on-board LED having tightly packed multiple chips together would be useful. More particularly, an optical element that can provide lighting having smaller variations in light intensity but varying angles from the LEDs would be beneficial. A lighting apparatus or lamp incorporating such an optical element would also be useful.

BRIEF DESCRIPTION OF THE INVENTION

0008The present invention provides an optical element for a lamp or lighting apparatus having at least one light emitting diode (LED) as a light source. Alternatively the source could be a Chip-On-Board (COB) LED which has closely packed multiple LED dies. The optical element is positioned proximate to the LED and receives light rays therefrom. In turn, the optical element distributes the substantially unidirectional (lambertian) light output from the LED into an omnidirectional output with a controlled variance in light intensity at different locations about the LED. A diffuser can also be used around the optical element and LED to provide further distribution of the light rays by e.g., light scattering. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

0009In one exemplary embodiment, the present invention provides a lighting apparatus that includes at least one light emitting diode and an optical element positioned adjacent to the at least one light emitting diode. The optical element defines a central axis and a lateral axis that is substantially orthogonal to the central axis. The optical element extends circumferentially about the central axis and includes a convex light receiving surface that is substantially symmetrical about the central axis and positioned adjacent to the at least one light emitting diode; a frustoconical light projecting surface positioned laterally outside of the convex light receiving surface and substantially symmetrical about the central axis; and an arcuate light reflecting surface positioned laterally inside of the frustoconical light projecting surface and substantially symmetrical about the central axis, the arcuate light reflecting surface spaced apart along the central axis from the convex light receiving surface.

0010In another exemplary embodiment, the present invention provides a lighting apparatus that includes at least one light emitting diode and an optical element positioned adjacent to the at least one light emitting diode. The optical element defines a central axis and a lateral axis that is substantially orthogonal to the central axis. The optical element extends circumferentially about the central axis and includes a light receiving surface that is substantially symmetrical about the central axis and positioned adjacent to the at least one light emitting diode, the light receiving surface forming an acute angle with the central axis; a light projecting surface that is substantially symmetrical about the central axis and spaced apart from the light receiving surface along the central axis; a frustoconical surface connected with the light projecting surface and substantially symmetrical about the central axis; and an arcuate light reflecting surface positioned laterally inside of the frustoconical surface and substantially symmetrical about the central axis, the arcuate light reflecting surface spaced apart along the central axis from the light receiving surface.

0011In still another exemplary embodiment, the present invention provides an optical element for a lighting apparatus having at least one light emitting diode. The optical element for positioning adjacent to the at least one light emitting diode. The optical element defines a central axis and a lateral axis that is substantially orthogonal to the central axis. The optical element extends circumferentially about the central axis. The optical element includes a light receiving surface that extends circumferentially about the central axis and is configured for positioning near the at least one light emitting diode. A frustoconical surface is spaced apart from the light receiving surface along the transverse direction and extends circumferentially about the central axis and is substantially symmetrical about the central axis. An arcuate light reflecting surface is positioned laterally inside of the frustoconical surface and extends circumferentially about the central axis and is substantially symmetrical about the central axis. The optical element is configured so that light from the at least one light emitting diode is emitted from the optical element with variation in light intensity measured at a fixed distance from central axis CA over the range of zero to 135 degrees that is not more than±twenty percent from the average light intensity measured from zero to 135 degrees.

0012These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

0013A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

0014<figref idref="DRAWINGS">FIG. 1</figref> provides a perspective view of an exemplary embodiment of an optical element of the present invention.

0015<figref idref="DRAWINGS">FIG. 2</figref> provides a cross-sectioned, perspective view of the exemplary embodiment of <figref idref="DRAWINGS">FIG. 1</figref>.

0016<figref idref="DRAWINGS">FIG. 3</figref> is a cross-sectional view of the exemplary embodiment of <figref idref="DRAWINGS">FIG. 1</figref> taken along line <b>3</b>-<b>3</b> of <figref idref="DRAWINGS">FIG. 1</figref>.

0017<figref idref="DRAWINGS">FIG. 4</figref> is a schematic view, along one side of central axis CA, of the exterior surface for the exemplary embodiment of <figref idref="DRAWINGS">FIG. 1</figref>.

0018<figref idref="DRAWINGS">FIG. 5</figref> is a schematic view representing the effect of the exemplary optical element of <figref idref="DRAWINGS">FIG. 1</figref> on light rays from certain light sources as further described herein.

0019<figref idref="DRAWINGS">FIG. 6</figref> is a graph depicting light intensity as a function of position for the exemplary embodiment of <figref idref="DRAWINGS">FIG. 1</figref> as will be further described herein.

0020<figref idref="DRAWINGS">FIG. 7</figref> is a perspective view of another exemplary embodiment of the present invention.

0021<figref idref="DRAWINGS">FIG. 8</figref> is a perspective view of another exemplary embodiment of an optical element of the present invention.

0022<figref idref="DRAWINGS">FIG. 9</figref> provides a cross-sectioned, perspective view of the exemplary embodiment of <figref idref="DRAWINGS">FIG. 8</figref>.

0023<figref idref="DRAWINGS">FIG. 10</figref> is a cross-sectional view of the exemplary embodiment of <figref idref="DRAWINGS">FIG. 8</figref> taken along line <b>10</b>-<b>10</b> of <figref idref="DRAWINGS">FIG. 10</figref>.

0024<figref idref="DRAWINGS">FIG. 11</figref> is a schematic view of the exterior surface for the exemplary embodiment of <figref idref="DRAWINGS">FIG. 8</figref>.

0025<figref idref="DRAWINGS">FIG. 12</figref> is a schematic view representing the effect of the optical element of <figref idref="DRAWINGS">FIG. 8</figref> on light rays from certain light sources as further described herein.

0026<figref idref="DRAWINGS">FIG. 13</figref> is a perspective view of the exemplary optical element and LEDs of <figref idref="DRAWINGS">FIG. 5</figref> with an exemplary diffuser.

DETAILED DESCRIPTION OF THE INVENTION

0027Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

0028An exemplary embodiment of a lens or optical element <b>100</b> of the present invention is shown in <figref idref="DRAWINGS">FIGS. 1 through 4</figref>. The optical element <b>100</b>, including certain surfaces as will be further described, is substantially symmetrical about a central axis CA and extends along circumferential direction C about central axis CA. For purposes of further describing this exemplary embodiment of the invention, optical element <b>100</b> defines a lateral direction L that extends substantially orthogonal to central axis CA. Optical element <b>100</b> may comprise a light transmissive material such as e.g., a glass, a polymer such as polycarbonate or an acrylic, or other light transmissive materials.

0029Optical element <b>100</b> includes a convex light receiving surface <b>102</b>. In a lighting apparatus such as a lamp, convex light receiving surface <b>102</b> would be positioned adjacent to, or in close proximity to, one or more LEDs and would allow light rays from such light source(s) to travel into optical element <b>100</b> (<figref idref="DRAWINGS">FIG. 5</figref>). Convex light receiving surface <b>102</b> extends circumferentially, and is substantially symmetrical about, central axis CA. As indicated in <figref idref="DRAWINGS">FIG. 4</figref>, for this exemplary embodiment, convex light receiving surface is defined by a radius R₁of about 11.75 mm. Other values for radius R₁may be used as well.

0030Convex light receiving surface <b>102</b> is part of a cylindrical portion <b>110</b> of optical element <b>102</b>. Cylindrical portion <b>110</b> includes a cylindrically-shaped surface <b>108</b> that is linear when viewed along the cross-section shown in <figref idref="DRAWINGS">FIG. 3</figref>. The length of cylindrical portion <b>110</b> along central axis CA may be varied to yield still other embodiments of the present invention.

0031Optical element <b>100</b> also includes a trumpet-shaped portion <b>112</b> that is adjacent to cylindrical portion <b>110</b> along the direction of central axis CA. Trumpet-shaped portion <b>112</b> includes frustoconical light projecting surface <b>104</b> that is positioned laterally outside of convex light receiving surface <b>102</b>. Surface <b>104</b> extends circumferentially around, and is substantially symmetrical about, central axis CA of optical element <b>100</b>. As shown in <figref idref="DRAWINGS">FIG. 4</figref>, for this exemplary embodiment, frustoconical light projecting surface <b>104</b> forms an acute angle with central axis CA and forms an angle θ₆with respect to lateral direction L. In one exemplary embodiment, angle θ₆form an angle in the range of about 50 degrees to about 70 degrees from lateral direction L. In another exemplary embodiment, angle θ₆is about 60 degrees.

0032Trumpet-shaped portion <b>112</b> also includes an arcuate light reflecting surface <b>114</b> that is positioned laterally inside of frustoconical light projecting surface <b>104</b>. Surface <b>114</b> extends circumferentially around, and is substantially symmetrical about, central axis CA of optical element <b>100</b>. Although shown as free form curve, arcuate light reflecting surface <b>114</b> can also be described with reference to angles θ₁, θ₂, θ₃, θ₄, and θ₅of <figref idref="DRAWINGS">FIG. 4</figref>. Each such angle θ_i, represents the angle relative to lateral direction L of a line tangent to surface <b>114</b> at locations <b>10</b>, <b>20</b>, <b>30</b>, <b>40</b>, and <b>50</b>. Locations <b>10</b>, <b>20</b>, <b>30</b>, <b>40</b>, <b>50</b> lie in a plane that includes central axis CA and lateral direction L and are spaced apart from each at equal distances along surface <b>114</b>.

0033For one exemplary embodiment, θ₁is about 63 degrees, θ₂is about 38 degrees, θ₃is about 24 degrees, θ₄is about 19 degrees, and <b>74</b>₅is about 14 degrees. In still another exemplary embodiment, θ₁is in the range of about 50 degrees to about 70 degrees, θ₂is in the range of about 30 degrees to about 50 degrees, θ₃is in the range of about 20 degrees to about 30 degrees, θ₄is in the range of about 10 degrees to about 30 degrees, and θ₅is in the range of about 10 degrees to about 30 degrees. Other shapes may be used for arcuate light reflecting surface <b>114</b> as well.

0034As shown in <figref idref="DRAWINGS">FIGS. 1 through 3</figref>, optical element <b>100</b> also includes a planar light projecting surface <b>106</b> that lies in a plane substantially perpendicular to central axis CA and substantially parallel to lateral axis L. Planar light projecting surface <b>106</b> is connected with frustoconical light projecting surface <b>104</b> at an edge <b>116</b> that extends circumferentially about central axis CA and is substantially symmetrical about central axis CA. Planar light projecting surface <b>106</b> is also connected with arcuate light reflecting surface <b>114</b> at an edge <b>118</b> that extends circumferentially about central axis CA, is substantially symmetrical about central axis CA, and is positioned laterally inward of edge <b>116</b>. Edge <b>118</b> is coincident with location <b>50</b> (<figref idref="DRAWINGS">FIG. 4</figref>).

0035Optical element <b>100</b> includes a conically-shaped surface <b>122</b> that is configured in a substantially symmetrical manner about central axis CA and is connected to arcuate light reflecting surface <b>114</b> at edge <b>124</b>. As shown, surface <b>122</b> opens along central axis CA in the direction of zero degrees. Edge <b>124</b> is coincident with location <b>10</b>.

0036Arcuate light reflecting surface <b>114</b> may be covered or coated with a highly reflective material different than the material used for the construction of body <b>120</b> of optical element <b>100</b>. For example, surface <b>114</b> may be metallized or covered with a coating of e.g., aluminum, silver, or other reflective metal. Other materials and/or techniques may be used as well. Similarly, conically-shaped surface <b>122</b> may also be covered or coated with a highly reflective material different than the material used for the construction of body <b>120</b>.

0037<figref idref="DRAWINGS">FIG. 5</figref> represents the simulated results obtained by placing optical element <b>100</b> closely adjacent to three light sources comprising LEDs <b>115</b>, <b>117</b>, and <b>119</b>. Alternatively, multiple light sources can be replaced by a chip-on-board (BOC) LED having multiple dies. By way of example, light rays <b>126</b> pass through convex light receiving surface <b>102</b>, pass through the material of body <b>120</b>, and are reflected off of arcuate light reflecting surface <b>114</b> at different angles. Light rays <b>128</b> pass through convex light receiving surface <b>102</b> and then pass through conically-shaped surface <b>122</b> at different angles. Some light rays <b>130</b> pass through convex light receiving surface <b>102</b> and then exit optical element <b>100</b> through planar light projecting surface <b>106</b>.

0038A lighting apparatus incorporating optical element <b>100</b> and one or more LEDs <b>115</b>, <b>117</b>, and <b>119</b> positioned adjacent thereto may also include a diffuser <b>136</b> as shown in <figref idref="DRAWINGS">FIG. 13</figref>. More particularly, diffuser <b>136</b> may be placed around optical element <b>100</b> to provide further scattering of the lights rays from the LED(s) and optical element <b>100</b> as will be understood by those skilled in the art. Diffuser <b>136</b> may, for example, by a constructed from a diffusive plastic material with low light absorption losses or as a glass bulb containing a phosphor and positioned around optical element <b>100</b> and one or more LEDs. Diffuser <b>136</b> may e.g., connect to heat sink and/or threaded (e.g., Edison) base (not shown).

0039Optical element <b>100</b> is configured to provide a more uniform distribution of light than is available from an LED light source, which provides substantially a single direction light output. More specifically, <figref idref="DRAWINGS">FIG. 6</figref> provides a simulated plot of light intensity (e.g., in candela) as a function of vertical angle from central axis CA for optical element <b>100</b>. Using lamp <b>133</b> for example, the plot represents the light intensity at angles from zero degrees to 180 degrees from central axis CA as shown (zero degrees and 180 degrees being coincident with central axis CA). As depicted in <figref idref="DRAWINGS">FIG. 6</figref>, for the exemplary embodiment of optical element <b>100</b>, the surfaces described above are configured so that the variation in light intensity measured at any distance from central axis CA over the range of zero to 135 degrees is not more than±twenty percent from the average light intensity measured from zero to 135 degrees. In another exemplary embodiment, such variation in light intensity is not more than±ten percent from the average light intensity at angles measured from zero to 150 degrees.

0040<figref idref="DRAWINGS">FIG. 7</figref> provides a perspective view of another exemplary embodiment of an optical element <b>200</b> of the present invention similar to the exemplary embodiment of <figref idref="DRAWINGS">FIGS. 1-4</figref> in that it includes convex light receiving surface <b>102</b>, frustoconical light projecting surface <b>204</b>, and arcuate light reflecting surface <b>214</b>. However, optical element <b>200</b> includes curved flutes <b>232</b> on light projecting surface <b>206</b> that extend in a substantially symmetrical manner about central axis CA and are circumferential about central axis CA. Additionally, a circular surface <b>236</b> located at central axis CA also includes a plurality of flutes <b>238</b> that extend in a substantially symmetrical manner about central axis CA and are circumferential about central axis CA. Flutes <b>232</b> and <b>238</b> provide additional light scattering. Other surface features such as e.g., pillows may also be used to provide additional light scattering.

0041Another exemplary embodiment of an optical element <b>300</b> of the present invention is shown in <figref idref="DRAWINGS">FIGS. 8</figref>, <b>9</b>, <b>10</b>, and <b>11</b>. <figref idref="DRAWINGS">FIG. 12</figref> illustrates this exemplary embodiment in conjunction with LEDs <b>315</b>, <b>317</b>, and <b>319</b>. Optical element <b>300</b>, including certain surfaces as will be further described, is substantially symmetrical about a central axis CA and extends along circumferential direction C about central axis CA. For purposes of further describing this exemplary embodiment of the invention, optical element <b>300</b> also defines a lateral direction L that extends substantially orthogonal to central axis CA. Optical element <b>300</b> is constructed from a light transmissive material such as e.g., a glass, a polycarbonate, an acrylic, or other light transmissive materials.

0042Optical element <b>300</b> includes a disc-shaped portion <b>310</b> and a trumpet-shaped portion <b>312</b>. Disc-shaped portion <b>310</b> includes a light receiving surface <b>302</b>. As shown, surface <b>302</b> is conical in shape and forms an acute angle with the central axis CA. However, light receiving surface <b>302</b> could also be curved in a convex manner. In a lighting apparatus such as a lamp, light receiving surface <b>302</b> would be positioned adjacent to, or in close proximity to, one or more LEDs and would allow light rays from such light source(s) to travel into optical element <b>300</b> (<figref idref="DRAWINGS">FIG. 12</figref>). Light receiving surface <b>302</b> extends circumferentially, and is substantially symmetrical about, central axis CA.

0043Disc-shaped portion <b>310</b> includes a cylindrically-shaped surface <b>308</b> that is linear when viewed along the cross-section shown in <figref idref="DRAWINGS">FIG. 10</figref>. The length of disc-shaped portion <b>310</b> along central axis CA may be varied to yield still other embodiments of the present invention. A light projecting surface <b>338</b> is connected to surface <b>308</b> and spaced apart from light receiving surface <b>302</b> along the direction of the central axis CA as shown. For the exemplary embodiments shown, light projecting surface <b>338</b> is frustoconical in shape. However, surface <b>328</b> may also be arcuate or convex in other embodiments of the invention. As shown in <figref idref="DRAWINGS">FIG. 11</figref>, for this exemplary embodiment, surface <b>338</b> forms an obtuse angle with central axis CA and forms an acute angle α₈with respect to lateral direction L. In one exemplary embodiment, angle α₈is about 25 degrees. In another exemplary embodiment, angle α₈is in the range of about 20 degrees to about 30 degrees.

0044Trumpet-shaped portion <b>312</b> is adjacent to disc-shaped portion <b>310</b> along the direction of central axis CA. Trumpet-shaped portion <b>312</b> includes frustoconical surface <b>304</b> that connected with light projecting surface <b>338</b>. Surface <b>304</b> extends circumferentially around, and is substantially symmetrical about, central axis CA of optical element <b>300</b> and is spaced apart along central axis CA from surface <b>338</b>. As shown in <figref idref="DRAWINGS">FIG. 11</figref>, for this exemplary embodiment, frustoconical surface <b>304</b> forms an acute angle with central axis CA and forms an angle α₇with respect to lateral direction L. In one exemplary embodiment, angle α₇is about 28 degree from lateral direction L. In another exemplary embodiment, angle α₇is in the range of about 23 degrees to about 33 degrees from lateral direction L.

0045Trumpet-shaped portion <b>312</b> also includes an arcuate light reflecting surface <b>314</b> that is positioned laterally inside of frustoconical surface <b>304</b>. Surface <b>314</b> extends circumferentially around, and is substantially symmetrical about, central axis CA of optical element <b>300</b>. Although shown as free form curve, arcuate light reflecting surface <b>314</b> can also be described with reference to angles α₂, α₃, α₄, α₅, and α₆of <figref idref="DRAWINGS">FIG. 11</figref>. Each such angle α_i, represents the angle relative to lateral direction L of a line tangent to surface <b>314</b> at locations <b>10</b>, <b>20</b>, <b>30</b>, <b>40</b>, and <b>50</b> as shown in <figref idref="DRAWINGS">FIG. 11</figref>. Locations <b>10</b>, <b>20</b>, <b>30</b>, <b>40</b>, <b>50</b> lie in a plane that includes central axis CA and lateral direction L and are spaced apart from each at equal distances along surface <b>314</b>.

0046For one exemplary embodiment, α₂is about 51 degrees, α₃is about 43 degrees, α₄is about 33 degrees, α₅is about 23 degrees, and α₆is about 15 degrees. In still another exemplary embodiment, α₂is in the range of about 46 degrees to about 56 degrees, α₃is in the range of about 38 degrees to about 48 degrees, α₄is in the range of about 28 degrees to about 38 degrees, α₅is in the range of about 18 degrees to about 28 degrees, and α₆is in the range of about 10 degrees to about 20 degrees. Other shapes may be used for surface <b>114</b> as well.

0047As shown in <figref idref="DRAWINGS">FIGS. 10 and 11</figref>, optical element <b>300</b> also includes a pair of adjacent frustoconical surfaces <b>340</b> and <b>342</b> that are substantially symmetrical about central axis CA and extend circumferentially about central axis CA. Surface <b>340</b> and <b>342</b> are connected between arcuate light reflecting surface <b>314</b> and frustoconical surface <b>304</b>.

0048Optical element <b>300</b> includes a conically-shaped surface <b>322</b> that is located in a substantially symmetrical manner along central axis CA and is connected to arcuate light reflecting surface <b>314</b> at edge <b>324</b>. As shown, surface <b>322</b> projects along central axis CA in the direction of zero degrees. Edge <b>324</b> is coincident with location <b>10</b>.

0049Arcuate light reflecting surface <b>314</b> may be covered or coated with a highly reflective material different than the material used for the construction of body <b>320</b> of optical element <b>300</b>. For example, surface <b>314</b> may be metallized or covered with a coating of e.g., aluminum, silver, or other reflective metal. Other materials and/or techniques may be used as well. Similarly, conically-shaped surface <b>322</b> may also be covered or coated with a highly reflective material different than the material used for the construction of body <b>320</b>.

0050<figref idref="DRAWINGS">FIG. 12</figref> represents the simulated results obtained by placing optical element <b>100</b> closely adjacent to three light sources comprising LEDs <b>315</b>, <b>317</b>, and <b>319</b>. By way of example, light rays <b>326</b> pass through light receiving surface <b>302</b>, pass through the material of body <b>120</b>, through surfaces <b>338</b> and <b>304</b>, and are reflected off of arcuate light reflecting surface <b>314</b> at different angles. Light rays <b>328</b> pass through light receiving surface <b>302</b> and then pass through conically-shaped surface <b>322</b> at different angles. Some light rays <b>330</b> pass through light receiving surface <b>102</b> and then exit optical element <b>300</b> through one or both of the pair of frustoconical surfaces <b>340</b> and <b>342</b>.

0051A lighting apparatus incorporating optical element <b>300</b> and one or more LEDs <b>115</b>, <b>117</b>, and <b>119</b> positioned adjacent thereto may also include a diffuser similar to diffuser <b>136</b> shown in <figref idref="DRAWINGS">FIG. 13</figref> with the exemplary embodiment <b>100</b>. Optical element <b>300</b> is equipped with a plurality of legs <b>344</b> that may be used to position and support element <b>300</b>.

0052As with previous embodiments, optical element <b>300</b> is configured to provide a more uniform distribution of light than is available from an LED light source. In a manner similar to that discussed above using <figref idref="DRAWINGS">FIG. 6</figref>, optical element <b>100</b> and the surfaces described above are configured so that the variation in light intensity measured at different angles from central axis CA over the range of zero to 135 degrees is not more than±twenty percent from the average light intensity measured at such fixed distance from zero to 135 degrees. In another exemplary embodiment, such variation in light intensity is not more than±ten percent from the average light intensity.

0053This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.